Snap hinges are known which are used particularly but not exclusively for the articulation of closure elements, such as for example the doors or access panels of pieces of furniture or cabinets of caravans, campers and the like, and which in passing from the closed configuration to the open configuration and vice versa rotate about a substantially horizontal axis.
With reference to the doors of wall-mounted cabinets, for example of caravans, campers or of certain kitchens, they generally lie on the vertical plane when they are in the closed configuration and on a horizontal or inclined plane when they are in the open configuration.
Known snap hinges include those provided with a double articulated quadrilateral and with two enclosed springs, which are arranged in series or in parallel and act on mutually opposite parts respectively of the two quadrilaterals or of one of them.
The two articulated quadrilaterals share a first lever and a second lever and have, as their base elements, respectively a coupling plate, which is designed to be fixed to a fixed component of the piece of furniture, cabinet or the like, and a plate for fixing to the closure element.
The coupling plate and the fixing plate lie on mutually parallel planes when the hinge is in the closed configuration and on mutually perpendicular or inclined planes when the hinge is in the open configuration.
Again with reference to the doors of wall-mounted cabinets, the coupling plate is fixed to the internal vertical face of the horizontal wall that delimits the cabinet in an upper region, while the fixing plate is fixed to the face of the door which, in the closed configuration of the cabinet, faces the inside of the cabinet.
Known hinges are provided with a fixing system which consists of threaded means, such as a plurality of screws which are inserted in a corresponding plurality of holes or slots formed through the coupling and fixing plates and engage respectively the component designed to be fixed and the closure element.
In some cases, known hinges are fixed to the component designed to be fixed and to the closure element before fitting such component and such element to the structure of the piece of furniture, cabinet or the like; in particular, the coupling plate is fixed to the fixed component before assembling the fixed component to the structure.
In other cases, instead, the coupling plate of the hinge is fixed to the fixed component, which is preassembled on the structure of the piece of furniture, cabinet or the like, and then the fixing plate is fixed to the closure element.
Once fixing has been performed, assembly errors are possible which relate in particular to the arrangement of the closure element (door) with respect to the fixed component.
In particular, the breadth of the gap between the facing edges of the closure element and of the fixed component may be incorrect.
If this breadth is greater than the optimum value, correct opening/closure of the hinge and of the closure element is prevented; moreover, gaps remain open which alter the aesthetics and architecture of the piece of furniture, cabinet or the like.
Further, errors in parallelism between the facing edges of the closure element and of the fixed component are frequent, the former being inclined with respect to the latter.
In all these cases it is necessary to disassemble the hinge, particularly the fixing plate, from the closure element and/or the coupling plate from the fixed component and perform a new and correct fixing thereof, unscrewing and screwing back in all the screws.
Therefore, these known hinges are not free from drawbacks, which include the fact that the current fixing system does not allow to adjust the position of the closure element with respect to the fixed component and the fact that it does not allow to compensate and correct positioning errors of the closure element with respect to the fixed component.
Another drawback of known hinges is that if the closure element is positioned incorrectly with respect to the fixed component, one is forced to disengage such hinge or hinges and to repeat the assembly operations, which are very laborious and imprecise, with a consequent waste of time.
Another drawback of known hinges is that the operations for assembling and dissembling the coupling plate with respect to the fixed component are very awkward and laborious, both due to the confined and limited maneuvering spaces and due to a limited visual field, which prevent the fitter, for example, from centering precisely the screw passage holes, reaching the various fixing screws, screwing and unscrewing correctly said screws, and handling easily the necessary tools.
Consider, for example, the case in which the coupling plate must be fixed to the internal vertical face of the horizontal wall that delimits in an upper region a wall-mounted cabinet; the fitter cannot check visually his work and cannot handle correctly the necessary tools unless he assumes a very awkward and uncomfortable position.